Tape cassette of high transparency material

ABSTRACT

A tape cassette has a cassette case with top face, under face, front face, rear face, and a pair of right and left side face portions. A pair of supply and take-up tape containers sides is provided in the cassette case. A tape is wound around a pair of reels and contained in the pair of tape containers. A first wall portion connects the rear and right side face portion with each other and forms part of the take-up side tape container. A second wall portion connects the rear and left side face portion with each other and forms part of the supply side tape container. A first prism portion extends from the rear face portion to the right side face portion and refracts or reflects light from a light emission element of a recording and reproducing apparatus for detecting presence and absence of the tape cassette.

This application is a continuation of Ser. No. 09/588,372, filed Jun. 7,2000, now U.S. Pat. No. 6,587,306.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tape cassette formed of a hightransparency material and having tape ends thereof detected and a tapecassette of which the presence/absence is detected.

2. Description of the Related Art

(Conventional Tape Cassette Regarding the Detection of a Tape End)

The applicant of the present application proposed a tape cassette, asthe conventional tape cassette of this type, disclosed by JapaneseUtility Model Examined Application Publication No. 63-25595. FIG. 1 is apartially-cut perspective view of the tape cassette; FIG. 2 is a planview of a lower case portion thereof; FIG. 3 is a perspective view ofpart S shown in FIG. 2; FIG. 4 is a perspective view of part E of FIG.2; and FIG. 5 is a perspective view of part F of FIG. 2.

In FIGS. 1 and 2, a cassette case 1 consists of a lower case portion 2and an upper case portion 3. The case portions 2 and 3 are assembledwith their respective junction surfaces abutting on each other. A pairof tape containers 4, 4 are provided in this cassette case 1. Reels 5, 5are rotatably arranged in the paired tape containers 4, 4, respectively.A tape (not shown) is wound around the paired reels 5, 5 and constitutedso that the rotation of the reels 5, 5 allows the traveling of the tape.Also, a cover lock container 6 is provided on one front end portion ofthe cassette case 1 to be surrounded by wall portions 10 d and 10 e. Acover lock member 7 is rockably arranged in the cover lock container 6.The cover lock member 7 locks a cover (not shown) to a closed position.While a cassette is inserted into a recording and reproducing apparatus,the position of the cover is changed to an unlocked position.

A light emission element insertion hole 11 is provided at the centralposition of the lower case 2 to be surrounded by the wall portion 10 a.While the tape cassette is being installed into the recording andreproducing apparatus, the light emission element 12 of the recordingand reproducing apparatus is arranged in the light emission insertionhole 11. The recording and reproducing apparatus is provided with a pairof right and left light reception elements 13 a and 13 b. The pairedlight reception elements 13 a and 13 b are positioned outward of theright and left sides of the tape cassette, respectively while the tapecassette is being installed into the recording and reproducingapparatus. The tape cassette is also provided with sensor optical pathholes 14 a to 14 e and 17 a to 17 d in wall portions 10 a to 10 e and 16a to 16 d, respectively, which are positioned on straight lines L1 andL2 coupling the position of the light emission element 12 with thepaired right and left light reception elements 13 a, and 13 b,respectively.

To be specific, the light which advances from the light emission element12 in right direction, is introduced into the tape container 4 by way ofthe sensor optical path hole 14 a of the right semicylindrical wallportion 10 a constituting the light emission element insertion hole 11and the sensor optical path hole 14 b of the wall portion 10 bconstituting tape container 4. FIG. 3 shows the sensor optical pathholes 14 a and 14 b provided in the lower case portion 2. It is notedthat sensor optical path holes (not shown) are also provided at thecorresponding positions of the upper case 3. To be exact, the holes ofthe upper and lower cases 2 and 3 constitute the respective sensoroptical path holes. After the light which is introduced into the tapecontainer 4 passes through the tape traveling path on which thepulled-out tape travels, the light is introduced to the outside of thetape cassette by way of the sensor optical path hole 14 c of the wallportion 10 c constituting the tape container 4, the sensor optical pathhole 14 d of the wall portion 10 d constituting the cover lock container6 and the sensor optical path hole 14 e of the wall portion 10 e on theside surface of the cassette (which wall portion also serves as oneconstituting the cover lock container 6) and reaches the light receptionelement 13 a. FIG. 4 shows the sensor optical path holes 14 c to 14 eprovided in the lower case portion 2. It is noted that sensor opticalpath holes are also provided at the corresponding positions of the uppercase portion 3 (except for the sensor optical path hole in the wallportion on the side surface of the cassette). To be exact, the holes ofthe upper and lower case portions 2 and 3 constitute the respectivesensor optical path holes.

The light which advances from the light emission element 12 in leftdirection, is introduced into the tape container 4 by way of the sensoroptical path hole 17 a of the left semicylindrical wall portion 16 a andthe sensor optical path hole 17 b of the wall portion 16 b constitutingthe tape container 4. FIG. 3 shows the sensor optical path holes 17 aand 17 b provided in the lower case portion 2. It is noted that sensoroptical holes (not shown) are also provided at the correspondingpositions of the upper case 3. To be exact, the holes of the upper andlower case portions 2 and 3 constitute the respective sensor opticalpath holes. After the light which is introduced into the tape container4 passes through a tape traveling path on which the pulled-out tapetravels, the light is introduced to the outside of the tape cassette byway of the sensor optical path hole 17 c of the wall portion 16 cconstituting the tape container 4, the sensor optical path hole 18 a ofa tape pad 18 which is a transparent member and the sensor optical pathhole 17 d of the wall portion 16 d on the side surface of the cassetteand reaches the light reception element 13 b. FIG. 5 shows the sensoroptical path holes 17 c and 17 d and the optical path hole 18 a of atape pad 18 provided in the lower case portion 2. It is noted thatsensor optical path holes are also provided at the correspondingpositions of the upper case portion 3, respectively (except for theoptical path hole in the wall portion on the side surface of thecassette). To be exact, the holes of the upper and lower case portions 2and 3 constitute the respective sensor optical path holes.

The wall portions 10 c to 10 e, 16 a to 16 d and the like whichconstitute the sensor optical path holes 14 c to 14 e and 15 a to 15 don the optical path for the light from the light emission element 12which comes out of the tape container 4, are colored with a low lightreflectance color. In FIGS. 4 and 5, the colored portions of the lowercase portion 2 are indicated by hatching. The corresponding portions ofthe upper case portion 3 are colored, as well.

With the above constitution, the light which advances from the lightemission element 12 in right direction reaches the tape traveling pathby way of the sensor optical path holes 14 a and 14 b. If a tape on thetape traveling path is a magnetic recording layer tape part, it does nottransmit light and the light does not reach the light reception element13 a. If the tape on the tape traveling path is a high lighttransmittance leader tape part, it transmits light and the light reachesthe light reception element 13 a by way of the sensor optical path holes14 c to 14 e. Further, the light which advances from the light emissionelement 12 in left direction reaches the tape traveling path by way ofthe sensor optical path holes 17 a and 17 b. If the tape on the tapetraveling path is a magnetic recording layer tape part, it does nottransmit light and the light does not reach the light reception element13 b. If the tape on the tape traveling path is a high lighttransmittance leader tape part, it transmits light and the light reachesthe light reception element 13 b by way of the sensor optical path holes17 c, 18 a and 17 d. Using the difference in the output voltages of thelight reception elements 13 a and 13 b between a case where the tape onthe tape traveling path is the magnetic recording layer tape part and acase where the tape is the leader tape part, it is detected whether thetape end is at a take-up side or a supply side.

Meanwhile, the light from the light emission element 12 contains notonly components advancing toward the light reception elements 13 a and13 b but also those which may be reflected by the flanges of the reels5, the inner surface of the cassette case 1 and the like and which mayreach the light reception elements 13 a and 13 b without passing thetape traveling path. Further, there are cases where external light isincident on the interior of the cassette case 1 from the windows or thelike on the upper surface of the tape containers 4 of the tape cassette,the incident light is reflected by the flanges of the reels 5, the innersurface of the cassette case 1 and the like and reaches the lightreception elements 13 a and 13 b without passing the tape travelingpath.

Here, if the cassette case 1 itself is formed out of a low lightreflectance material such as a black material, the quantity of lightwhich reaches the light reception elements is very small. Due to this,the light reception elements 13 a and 13 b, less likely, malfunction.Conversely, if the cassette case 1 itself is desired to be formed out ofa material having high light reflectance or high transparency, thequantity of the above-stated unnecessary light which reaches the lightreception elements 13 a and 13 b becomes disadvantageously large.

In spite of the above fact, according to the conventional case, portionsclose to the light reception elements 13 a and 13 b are colored with alow light reflectance color, thereby making it possible to sufficientlyattenuate the unnecessary light at those positions and to prevent thelight reception elements 13 a and 13 b from malfunctioning. In otherwords, it is possible to produce a colorful tape cassette without theneed to consider the color of the cassette case 1 and the like.

(Tape Cassette Regarding the Detection of the Presence/Absence of theTape Cassette)

The tape cassette is employed in various apparatuses beside therecording and reproducing apparatus. They involve, for example, anoperational cassette changer for a duplicator. FIGS. 6 and 7 show anexample of usage of the cassette changer. In FIGS. 6 and 7, a recordingand reproducing apparatus 101 is a tape dubbing apparatus having twocassette drives and the like. A cassette changer 103 is coupled to onecassette insertion port of the recording and reproducing apparatus 101through a coupling portion 102.

The cassette changer 103 has a cassette tray 105 slidably arranged in achanger main body 104. The cassette tray 105 is moved between a cassettereference position and the cassette delivery position of the recordingand reproducing apparatus 101. A pair of cassette stoppers 107 areprovided above the cassette tray 105 so as to hold a tape cassette 106at a cassette set position. The paired cassette stoppers 107 are movedto be apart from each other (in arrow directions shown in FIG. 6B),whereby the tape cassette 106 drops into the cassette tray 105 whilebeing guided by rollers 108.

A cassette press arm 110 sliding along a guide rail 109 is also providedat the changer main body 104. The cassette press arm 110 presses theside surface of the tape cassette 106, whereby the tape cassette 106 canbe moved from the cassette reference position of the cassette tray 105to a cassette eject position (cassette position) on a storage 111. Thestorage 111 is provided laterally of the cassette tray 105. The changermain body 104 is provided with cassette presence detection means 112 fordetecting whether or not the tape cassette 106 is at the cassetteejection position on the storage.

The cassette presence detection means 112 has a light emission portion112 a and a light reception portion 112 b receiving a detected lightfrom the light emission portion 112 a. The optical path CC of thedetected light which has reached the light reception portion 112 b fromthe light emission portion 112 a is set to pass the cassette ejectionposition which is the cassette position.

Next, the function of the above-stated constitution will be described.As indicated by virtual lines shown in FIGS. 6A and 6B, the tapecassette 106 is set at the cassette position. In a start mode, thepaired cassette stoppers 107 are moved to be away from each other andthe tape cassette 106 drops into the cassette reference position on thecassette tray 105. Then, the cassette tray 105 moves to the cassettedelivery position of the recording and reproducing apparatus 101 and thetape cassette 106 is installed into the recording and reproducingapparatus 101, thereby starting dubbing. When dubbing is finished, thetape cassette. 106 is ejected from the recording and reproducingapparatus 101 and returned onto the cassette tray 105. Thereafter, thecassette tray 105 is moved to the cassette reference position and thetape cassette 106 at the cassette reference position is pressed by thecassette press arm 110 and ejected to the cassette ejection position (astate shown in FIGS. 7A and 7B).

If the next tape cassette 106 is put at the cassette set position, astart mode is selected and dubbing is executed through the sameoperation process stated above. If a user removes the tape cassette 106from the cassette ejection position, detected light from the lightemission portion 112 a is not shielded by the tape cassette 106 andreaches the light reception portion 112 b. Thus, the cassette presencedetection means 112 detects that the tape cassette 106 is not at thecassette ejection position and then the tape cassette 106 is ejected tothe cassette ejection position through the same operation process statedabove. On the other hand, if the user does not remove the tape cassette106 completed with dubbing from the cassette ejection position, detectedlight from the light emission portion 112 a is shielded by the tapecassette 106 and does not reach the light reception portion 112 b. Thus,the cassette presence detection means 112 detects that the tape cassette106 is at the cassette ejection position, whereby even if there is atape cassette 106 to be completed with dubbing, the tape cassette 106 isprohibited from being ejected to the cassette ejection position.

(Tape Cassette Regarding the Detection of a Tape End)

According to the above-stated conventional tape cassette, it is requiredto color the portions of the cassette case 1 near the light receptionelements 13 a and 13 b. Due to this, a coloring step which is quitelaborious is included in processing steps, with the result thatproduction efficiency disadvantageously, greatly deteriorates and demandfor mass production cannot be disadvantageously met.

Further, there is demand for forming the cassette case 1 itself out of ahigh transparency material. In that case, if the portions of thecassette case 1 are colored with a low light reflectance color, thecolor disadvantageously differs from an originally intended color.

(Tape Cassette Regarding the Detection of Presence/Absence of the TapeCassette)

If there is demand for forming the cassette case itself of the cassette106 out of high transparency material and the tape cassette 106 isformed according to the demand, there is a possibility that a detectionerror occurs to the cassette presence detection means 112 describedabove. That is, even if the tape cassette 106 is at the cassetteejection position, the detected light from the light emission portion112 a transmits the cassette case and reaches the light receptionportion 112 b and the cassette presence detection means erroneouslydetects that the cassette is absent. If such an erroneous detection ismade, the next tape cassette 106 is fed to the cassette ejectionposition even while the tape cassette 106 is at the cassette ejectionposition. As a result, the earlier tape cassette 106 drops from thestorage 111 and damaged or, if the storage 111 has a drop preventivewall, a heavy load is applied to the cassette press arm 110 and thecassette changer 103 and the like are damaged.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a tapecassette to solve the above-stated problems and capable of preventingmalfunction in tape end detection irrespectively of the characteristics(color, transparency and reflectance) of a cassette case without extremedeterioration of production efficiency and capable of maintaining acolor originally intended for the cassette case as much as possible ifthe cassette case itself is formed out of a high transparency material.

It is also an object of the present invention to provide a tape cassetteto solve the above-stated problems and capable of preventing a cassettedetection error even if a cassette case is formed out of a hightransparency material.

To achieve the above object, there is provided a tape cassette having apair of reels rotatably provided in a pair of tape containers,respectively, a tape being wound around the pair of reels and containedin the pair of tape containers, the tape consisting of a magneticrecording layer tape part and high light transmittance leader tape partsadded to both ends of the tape, respectively, and having sensor opticalpath holes provided on wall portions, respectively, on a straight linecoupling a position of a light emission element of a recording andreproducing apparatus with a position of a light reception element ofthe recording and reproducing apparatus so that light from the lightemission element is introduced into the tape containers and lightpassing through tape running paths of the tape containers comes out ofthe tape containers and reaches the light reception element while thetape cassette is installed into the recording and reproducing apparatus,wherein a light shielding portion having a light shielding effect isprovided around at least one of the sensor optical path hole right afterthe light from the light emission element comes out of one of the tapecontainers and next the sensor optical path hole.

According to the present invention, since a light shielding portionhaving a light shielding effect is provided around at least one of thesensor optical path hole right after the light from the light emissionelement comes out of one of the tape containers and next the sensoroptical path hole, it suffices to provide light shielding portionsaround the two sensor optical path holes at most. Thus, it is possibleto prevent malfunction in tape end detection irrespectively of thecharacteristics (color, transparency and reflectance) of the cassettecase, capable of responding to the demand of mass production withoutgreatly deteriorating production efficiency, and capable of maintaininga color originally intended for the cassette case as much as possible ifthe cassette case itself is formed out of a high transparency material.

In a preferred embodiment of the present invention, the light shieldingportion is provided to have right and left widths of about not less than1 mm from a center of an optical path coupling the position of the lightemission element with the position of the light reception element by thestraight line and to spread over an entire height of at least one of thewall portion right after the light from the light emission element comesout of one of the tape containers and the next wall portion.

According to this embodiment, it is possible to ensure preventingmalfunction in tape end detection.

In a preferred embodiment of the present invention, the light shieldingportion is formed out of a light shielding member bonded to at least oneof the wall portion right after the light from the light emissionelement comes out of one of the tape containers and the next wallportion.

According to this embodiment, since it suffices to bond the lightshielding members to two wall portions at most, it can be expected thatproduction efficiency further enhances.

In a preferred embodiment of the present invention, the light shieldingportion is constituted by forming the wall portion right after the lightfrom the light emission element comes out of at least one of the tapecontainers and the next wall portion itself, out of a light shieldingmember to be colored with two colors when forming a cassette case.

According to this embodiment, since it suffices to form the cassettecase to be colored with two colors, it can be expected that productionefficiency further enhances.

In a preferred embodiment of the present invention, the light shieldingportion is constituted by attaching a light shielding holder having thesensor optical path hole to at least one of the wall portion right afterthe light from the light emission element comes out of at least one ofthe tape containers and the next wall portion.

According to this embodiment, since it suffices to attach the lightshielding holders to two wall portions at most, it can be expected thatproduction efficiency further enhances.

Further, to achieve the above object, there is provided a tape cassettehaving a pair of reels rotatably provided in a pair of tape containers,respectively, a tape being wound around the pair of reels and containedin the pair of tape containers, the tape consisting of a magneticrecording layer tape part and high light transmittance leader tape partsadded to both ends of the tape, respectively, and having sensor opticalpath holes provided on wall portions, respectively, on a straight linecoupling a position of a light emission element of a recording andreproducing apparatus with a position of a light reception element ofthe recording and reproducing apparatus so that light from the lightemission element is introduced into the tape containers, light passingthrough tape running paths of the tape containers comes out of the tapecontainers, passes through a cover lock container and reaches the lightreception element while the tape cassette is installed into therecording and reproducing apparatus, wherein a cylindrical protrusionhaving a light shielding effect is provided at a cover lock memberarranged in the cover lock container, and a sensor optical path holearranged on the straight line coupling the position of the lightemission element with the position of the light reception element isprovided at the cylindrical protrusion while the cover lock member is atan unlock position.

According to the present invention, even if unnecessary light isincident on the sensor optical path hole of the cylindrical protrusion,it abuts on the inner surface of the sensor optical path hole andshielded by the absorption effect thereof. Thus, it is possible toprevent malfunction in tape end detection irrespectively of thecharacteristics (color, transparency and reflectance) of the cassettecase, capable of responding to the demand of mass production withoutgreatly deteriorating production efficiency, and capable of maintaininga color originally intended for the cassette case as much as possible ifthe cassette case itself is formed out of a high transparency material.

Moreover, to achieve the above object, there is provided a tape cassettehaving a pair of reels rotatably provided in a pair of tape containers,respectively, a tape wound around the pair of reels and contained in thepair of tape containers, the tape consisting of a magnetic recordinglayer tape part and high light transmittance leader tape parts added toboth ends of the tape, respectively, and having sensor optical pathholes provided on wall portions on a straight line coupling a positionof a light emission element of a recording and reproducing apparatuswith a position of a light reception element of the recording andreproducing apparatus so that light from the light emission element isintroduced into the tape containers and light passing through taperunning paths of the tape containers comes out of the tape containersand reaches the light reception element while the tape cassette isinstalled into the recording and reproducing apparatus, wherein at leastone of an upper flange and a lower flange of each of the pair of reelsis formed out of a reflection light attenuating material and areflection light attenuating color.

According to the present invention, since unnecessary light abuts on theflange portions of the reels and shielded by the absorption effectthereof, it is possible to prevent malfunction in tape end detectionirrespectively of the characteristics (color, transparency andreflectance) of the cassette case, capable of responding to the demandof mass production without greatly deteriorating production efficiency,and capable of maintaining a color originally intended for the cassettecase as much as possible if the cassette case itself is formed out of ahigh transparency material.

Furthermore, to achieve the above object, there is provided a tapecassette provided with a light emission portion and a light receptionportion for receiving detection light from the light emission part at anapparatus side, an optical path of the detection light reaching thelight reception portion from the light emission portion set to pass acassette position, and used with an apparatus for detecting presence andabsence of the tape cassette depending on whether the detection lightfrom the light emission portion reaches the light reception portion,wherein a cassette case is formed out of a high transparency material,and a prism portion for refracting or reflecting incident light in anemission direction in which the incident light does not reach the lightreception portion is provided at a position of the cassette case on theoptical path of the detection light.

According to the present invention, if the tape cassette is at thecassette position, the detection light from the light emission portionis refracted or totally reflected by the prism portion and does notreach the light reception portion. Thus, it is possible to prevent acassette detection error in the tape cassette with a high transparencycassette case.

In a preferred embodiment of the present invention, the prism portion isformed integrally with the cassette case.

According to this embodiment, since the prism portion is formedsimultaneously with the cassette case, the prism portion can be easilyproduced at low cost. In addition, compared with a case of providing alight shielding member at the position of the prism portion, thisembodiment has advantages in that an assembly step is not necessary andproblems such as attachment error, peeling and the like can be avoided.

In a preferred embodiment of the present invention, the prism portion isprovided at a position of the cassette case on which the detection lightemitted from the light emission portion is incident first.

According to this embodiment, since the distance from the prism portionto the light reception portion is long and it is possible to prevent thedetection light from reaching the light reception portion even if aprism deviation angle is set small, the degree of freedom for prismdesign increases.

In addition, to achieve the above object, there is provided a tapecassette provided with a light emission portion for cassette presenceand absence detection and a light reception portion for cassettepresence and absence detection receiving detection light from the lightemission part at an apparatus side, an optical path of the detectionlight reaching the light reception portion from the light emissionportion set to pass a cassette position, and used with an apparatus fordetecting presence and absence of the tape cassette depending on whetherthe detection light from the light emission portion reaches the lightreception portion, and provided with a light emission portion forcassette end detection and a light reception portion for cassette enddetection receiving detection light from the light emission portion atan apparatus side, and used with an apparatus for detecting presence andabsence of a tape end depending on whether the detection light from thelight emission portion reaches the light reception portion, wherein alight shielding member is provided on an optical path for tape enddetection to block passage of unnecessary light deviated from theoptical path; and the light shielding member is extended and an extendedportion of the light shielding member is arranged on an optical path forcassette presence and absence detection.

According to the present invention, the prevention of malfunction intape end detection is ensured for a high transparency cassette case, andfurther it is possible to prevent a cassette detection error withoutincreasing the number of parts and deteriorating assemblage.

Further, to achieve the above object, there is provided a tape cassetteused with an apparatus for detecting a tape terminal end depending onwhether tape end detection light from a light emission portion reaches alight reception portion, wherein a prism portion for refracting orreflecting the tape end detection light from the light emission portionin an emission direction in which the light does not reach the lightreception portion, is provided on a wall around an optical path notchthrough which the tape end detection light passes.

According to the present invention, since the tape end detection lightfrom the light emission portion is refracted or totally reflected by theprism portion and does not reach the light reception portion, it ispossible to prevent a cassette detection error in a tape cassette with ahigh transparency cassette case.

Also, to achieve the above object, there is provided a tape cassetteprovided with two light emission portions for cassette presence andabsence detection and two light reception portions for cassette presenceand absence detection receiving detection lights from the light emissionportions at an apparatus side, first and second optical paths of firstand second detection lights reaching the light reception portions fromthe light emission portions, respectively, set to pass a cassetteposition, and used with an apparatus for detecting presence and absenceof the tape cassette depending on whether the first detection light andsecond detection light from the respective light emission portions reachthe respective light reception portions; and provided with two lightemission portions for tape end detection and two light receptionportions for tape end detection receiving detection lights from thelight emission portions at an apparatus side, third and fourth opticalpaths of third and fourth detection lights reaching the light receptionportions from the light emission portions, respectively, set to pass thetape position, and used with an apparatus for detecting presence andabsence of a tape end depending on whether the third detection light andfourth detection light from the light emission portions reach therespective light reception portions, wherein a cassette case is formedout of a high transparency material; prism portions for refracting orreflecting the first and second detection lights for cassette presenceand absence detection in a direction in which the first detection lightand second detection light do not reach the respective light receptionportions, are provided at positions of the cassette case on first andsecond optical paths of the first and second lights for cassettepresence and absence detection, respectively; and light shieldingmembers are provided on third and fourth optical paths of third andfourth lights for tape end detection to block passage of unnecessarylight deviated from the third and fourth optical paths, respectively.

According to the present invention, it is possible to ensure preventingmalfunction in tape end detection for a high transparency cassette caseand to prevent a tape cassette presence/absence detection error.

Moreover, to achieve the above object, there is provided a tape cassetteprovided with two light emission portions for cassette presence andabsence detection and two light reception portions for cassette presenceand absence detection receiving detection lights from the light emissionportions at an apparatus side, first and second optical paths of firstand second detection lights reaching the light reception portions fromthe light emission portions, respectively, set to pass a cassetteposition, and used with an apparatus for detecting presence and absenceof the tape cassette depending on whether the first detection light andsecond detection light from the respective light emission portions reachthe respective light reception portions; and provided with two lightemission portions for tape end detection and two light receptionportions for tape end detection receiving detection lights from thelight emission portions at an apparatus side, third and fourth opticalpaths of third and fourth detection lights reaching the light receptionportions from the light emission portions, respectively, set to pass thetape position, and used with an apparatus for detecting presence andabsence of a tape end depending on whether the third detection light andfourth detection light from the light emission portions reach therespective light reception portions, wherein a cassette case is formedout of a high transparency material; a prism portion for refracting orreflecting the first detection light for cassette presence and absencedetection in a direction in which the first detection light does notreach the light reception portion, is provided at a position of thecassette case on a first optical path of the first detection light; afirst light shielding member is provided on a second optical path of thesecond detection light for cassette presence and absence detection, asecond light shielding member is provided on a third optical path of thethird detection light for tape end detection to block unnecessary lightdeviated from the third optical path; and a third light shielding memberis provided on a fourth optical path of the fourth detection light fortape end detection to block unnecessary light deviated from the fourthoptical path.

According to the present invention, it is possible to ensure preventingmalfunction in tape end detection for a high transparency cassette caseand to prevent a tape cassette presence/absence detection error.

In a preferred embodiment of the present invention, the first lightshielding member is extended and an extended portion of the first lightshielding member is set as the second light shielding member.

According to this embodiment, it is possible to reduce the number ofparts and the number of assembly steps and to enhance productionefficiency.

The nature, principle and utility of the invention will become moreapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 shows prior art regarding the detection of a tape and is apartially cut perspective view of a tape cassette;

FIG. 2 shows prior art regarding the detection of a tape and is a planview of a lower case portion;

FIG. 3 shows prior art regarding the detection of a tape and is aperspective view of part S of FIG. 2;

FIG. 4 shows prior art regarding the detection of a tape and is aperspective view of part E of FIG. 2;

FIG. 5 shows prior art regarding the detection of a tape and is aperspective view of part F of FIG. 2;

FIGS. 6A and 6B are a plan view and a front view, respectively showing astate in which a conventional cassette changer is used;

FIGS. 7A and 7B are a plan view and a front view, respectively showing astate in which a conventional cassette changer is used;

FIG. 8A shows the first embodiment of the present invention and is aplan view of a lower case portion;

FIG. 8B is a perspective view of part E of FIG. 8A;

FIG. 9 shows the first embodiment of the present invention and is aschematically longitudinal sectional view of a tape cassette;

FIG. 10 is a perspective view of the important parts of a lower caseportion in the second embodiment according to the present invention;

FIG. 11 is a perspective view of the important parts of a lower caseportion in the third embodiment according to the present invention;

FIG. 12 is a perspective view of the important parts of a lower caseportion in the fourth embodiment according to the present invention;

FIG. 13 is a perspective view of the important parts of a lower caseportion in the fifth embodiment according to the present invention;

FIG. 14 show the fifth embodiment of the present invention and is aperspective view of a light shielding holder;

FIG. 15 shows the sixth embodiment of the present invention and is aperspective view of the important parts of a lower case portion;

FIGS. 16A and 16B shows the seventh embodiment of the present inventionand are a side view and a front view of a cover lock member,respectively;

FIG. 17A is a sensor output characteristic view while the white(transparent) cassette case is used and the right and left widths (lightshielding range widths) of the light shielding portion are changed inthe first to sixth embodiments;

FIG. 17B shows the right and left widths (light shielding range widths)of the light shielding portion;

FIG. 18 shows a list of malfunction evaluation results of the first andsecond embodiments and the comparison examples;

FIG. 19 shows the eighth embodiment of the present invention and is aschematic cross-sectional view of a tape cassette;

FIG. 20 shows the eighth embodiment of the present invention and is aperspective view of the important parts (corresponding to part F of FIG.8A) of a lower case portion;

FIG. 21 shows the ninth embodiment of the present invention and is aperspective view of the important parts of the lower case portion;

FIG. 22 shows the tenth embodiment of the present invention and is aperspective view of the important parts of the lower case portion;

FIG. 23 shows the tenth embodiment of the present invention and is aperspective view of a tape pad;

FIG. 24 shows the eleventh embodiment of the present invention and is aperspective view of the important parts of the lower case portion;

FIG. 25 shows the twelfth embodiment of the present invention and is aperspective view of the important parts of the lower case portion;

FIG. 26 shows a list of malfunction evaluation results of the eighth toeleventh embodiments and the comparison examples;

FIG. 27 shows the thirteenth embodiment of the present invention and isa schematically cross-sectional view of a tape cassette;

FIGS. 28A to 28C show the fourteenth embodiment of the presentinvention, wherein FIG. 28A is a plan view of a tape cassette from whichonly the upper surface portion of a cassette case is removed, FIG. 28Bis a back view of the tape cassette and FIG. 28C is a side view of thetape cassette;

FIG. 29 shows the fourteenth embodiment of the present invention andshows the part of MM of FIG. 28A in partial enlargement view;

FIG. 30 shows the fourteenth embodiment of the present invention andshows the optical path of detection light incident on the prism portionon the side surface portion;

FIG. 31 shows the fourteenth embodiment of the present invention andshows the optical path of detection light incident on the prism portionon the back surface portion;

FIG. 32 shows the fifteenth embodiment of the present invention andshows prism portions arranged in part MM of FIG. 28A in partialenlargement view;

FIGS. 33A to 33C show the sixteenth embodiment of the present invention,wherein FIG. 33A is a plan view of a tape cassette from which only theupper surface portion of a cassette case is removed, FIG. 33B is a backview of the tape cassette and FIG. 33C is a side view of the tapecassette;

FIG. 34 shows the sixteenth embodiment of the present invention and is apartial enlargement view of part NN of FIG. 33C;

FIG. 35 show the sixteenth embodiment of the present invention and showthe optical path of detection light incident on the prism portion on thebottom portion;

FIGS. 36A to 36C show the seventeenth embodiment of the presentinvention, wherein FIG. 36A is a plan view of a tape cassette from whichonly the upper surface portion of a cassette case is removed, FIG. 36Bis a back view of the tape cassette and FIG. 36C is a side view of thetape cassette;

FIG. 37 shows the eighteenth embodiment of the present invention and apartial plan view of a tape cassette from which only the upper surfaceportion of a cassette case is removed;

FIG. 38 shows the eighteenth embodiment of the present invention and isa perspective view of important parts showing a state before the lightshielding member is attached;

FIG. 39 shows the eighteenth embodiment of the present invention and isa perspective view of important parts showing a state the lightshielding member has been attached;

FIG. 40 shows the nineteenth embodiment of the present invention and aplan view of a tape cassette from which only the upper surface portionof a cassette case is removed;

FIGS. 41A to 41C show the nineteenth embodiment of the presentinvention, wherein FIG. 41A is an explanatory view of the surrounding ofthe optical path notch of the cassette case of the tape cassette, FIG.41B shows the optical path of tape end detection light if the prismportion is provided and FIG. 41C shows the optical path of tape enddetection light if the prism portion is not provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments of the present invention will be described hereinafterwith reference to the accompanying drawings.

(Embodiments of a Tape Cassette Regarding the Detection of a Tape End)

First to seventh embodiments concern the constitution of a tape cassetterelating to the detection of a tape end at a take-up side (tape windingside); eighth to twelfth embodiments concern the constitution thereofrelating to the detection of a tape end at a supply side (tape supplyside); and the thirteenth embodiment concerns the constitution thereofrelating to the detection of tape ends at both the take-up side and thesupply side, i.e., the constitution of the tape cassette which dealswith both the take-up side and the supply side.

FIGS. 8A, 8B and 9 show the first embodiment of the present invention.Specifically, FIG. 8A is a plan view of a lower case portion 2, FIG. 8Bis a perspective view of part E of FIG. 8A and FIG. 9 is a schematicallylongitudinal sectional view of the tape cassette. In FIGS. 8A, 8B and 9,the same constituent elements as those described in the conventionaltape cassette regarding the detection of a tape end will not describedherein to avoid repetitive description and only different constituentelements will be described. It is noted that the same constituentelements as those of the conventional tape cassette regarding thedetection of the tape end are denoted by the same reference symbols tohelp understand the invention. The same thing is true for the otherdrawings.

In the first embodiment, a portion close to a light reception element 13a is not colored with a low light reflectance color unlike theconventional tape cassette but a light shielding member 20, serving as alight shielding portion 15, is bonded around a sensor optical path hole14 c just after light from a light emission element 12 comes out of atape container 4 at a right side (take-up side), as shown in FIG. 8B.The light shielding member 20 is formed out of a light shieldingmaterial with a light shielding color and a sensor optical path hole 21is provided on a portion corresponding to a sensor optical light hole 14c.

The light shielding member 20 is provided to have right and left widthsD each of not less than about 1 mm from the center of an optical pathcoupling the position of the light emission element 12 with that of thelight reception element 13 a by a straight line L1 and to spread overthe entire height of a wall portion 10 c. The reason for setting each ofthe right and left widths D at not less than about 1 mm will bedescribed later in detail.

Although FIG. 8B only illustrates the lower case portion 2, an uppercase portion 3 has a wall portion (not shown) at an opposite position tothat of the wall portion 10 c, as well. The entire height of the wallportion 10 c means a total of the heights of the upper and lower caseportions 2 and 3. Although the following drawings illustrate only thelower case portion 2, too, the upper case portion 3 has wall portions(not shown) at opposite positions, respectively. If the wall portionsare processed, the same process is conducted thereto as that of the wallportions of the lower case portion. Further, the light shielding portion15 to be described in the second and the following embodiments is alsoprovided to have right and left widths D each of about not less than 1mm from the center of an optical path coupling the position of the lightemission element 12 with that of the light reception element 13 a by thestraight light L1 and to spread over the entire height of the wallportion 10 c.

With the above-stated constitution, light 22 advancing straight to thelight reception element 13 a, among the light from the light receptionelement 12, reaches a tape traveling path by way of sensor optical pathholes 14 a and 14 b. If a tape T on the tape traveling path is amagnetic recording layer tape part, the tape T does not transmit lightand the light does not, therefore, reach the light reception element 13a. If the tape T is a high light transmittance leader tape part, ittransmits light and the light reaches the light reception element 13 aby way of sensor optical path holes 14 c to 14 e.

Further, among light from the light emission element 12, unnecessarylight 23 which does not advance straight to the light reception element13 a and unnecessary light 23 incident into the cassette case 1 from awindow or the like on the upper surface of the tape container 4 of thetape cassette may be reflected by the upper and lower flanges 5 a and 5b of a reel 5, the inner surface of the cassette case 1 and the like anddirected toward the light reception element 13 a without passing thetape traveling path. Since most of the unnecessary light 23 which maypossibly reach the light reception element 13 a is abutted against thelight shielding member 20 and then shielded by the member 20, the ratioof the unnecessary light which reaches the light reception element 13 ais very low.

Accordingly, it is possible to prevent malfunction in the detection of atape end irrespectively of the characteristics (color, transparency andreflectance) of the cassette case 1. In the production of a tapecassette, it suffices to simply bond the light shielding member 20 tothe wall portion 10 c. Unlike the conventional tape cassette, therefore,the production efficiency of the tape cassette in this embodiment doesnot deteriorate greatly. Furthermore, the light shielding member 20 maybe bonded to only one wall portion 10 c which is not on the outersurface of the cassette case 1. Therefore, if the cassette case itselfis made of a high transparency material, a color originally intended forthe cassette case 1 can be maintained as much as possible.

FIG. 10 is a perspective view of the important parts of the lower caseportion 2 in the second embodiment according to the present invention(corresponding to FIG. 8B). In the second embodiment shown in FIG. 10, alight shielding member 20 serving as a light shielding portion 15 isbonded not to a portion just after light from a light emission element12 comes out of a tape container 4 but bonded around the next sensoroptical path hole 14 d. In FIG. 10, the light shielding member 20 isshown bonded to a wall portion 10 d at a wall portion 10 c side.Needless to say, the member 20 may be bonded to a wall portion 10 d at awall portion 10 e side. The remaining constituent elements are the sameas those in the first embodiment, which description will not be,therefore, given herein.

It can be expected that the second embodiment provides the same functionand advantages as those of the first embodiment.

As a modification of the first and second embodiments, the lightshielding member 20 may be bonded around the sensor optical path hole 14c right after light from the light emission element 12 comes out of thetape container 4 and the next sensor optical path hole 14 d. Since thismodification can further enhance unnecessary light shielding effect, itis possible to further prevent malfunction in detecting the tape end ofa tape T. In this case, however, the light shielding member 20 is bondedto the two portions and is slightly disadvantageous in productionefficiency. Nevertheless, the production efficiency of this modificationis sufficiently advantageous over the conventional cassette case.

FIG. 11 is a perspective view of the important parts of a lower caseportion 2 in the third embodiment of the present invention(corresponding to FIG. 8B). In the third embodiment shown in FIG. 1, alight shielding portion 15 is provided around a sensor optical path hole14 c right after light from a light emission element 12 comes out of atape container 4. This light shielding portion 15 is constituted byforming a wall portion 10 c itself out of a light shielding member withtwo colors in the formation of a cassette case 1. FIG. 11 shows that alight shielding material portion is indicated by hatching.

In the third embodiment as in the case of the first embodiment, it ispossible to prevent malfunction in the detection of a tape endirrespectively of the characteristics (color, transparency andreflectance) of the cassette case 1. Besides, if the cassette case 1itself is formed out of a high transparency material, a color originallyintended for the cassette case 1 can be maintained as much as possible.Furthermore, since it suffices to form the wall portion 10 c with twocolors in the production of the tape cassette, production efficiencydoes not extremely deteriorate differently from the conventional tapecassette.

FIG. 12 is a perspective view of the important parts of a lower caseportion 2 in the fourth embodiment of the present invention(corresponding to FIG. 8B). The fourth embodiment shown in FIG. 12differs from the third embodiment in that not a wall portion right afterlight from a light emission element 12 comes out of the tape container 4but the next wall portion 10 d is colored with two colors. The remainingconstituent elements are the same as those in the third embodiment,which description will not be, therefore, given herein.

It can be expected that the fourth embodiment provides the same functionand advantages as those of the third embodiment.

As a modification of the third and fourth embodiments, the wall portion10 c right after light from the light emission element 12 comes out ofthe tape container 4 and the next wall portion 10 d may be formed out ofa light shielding material and to be colored with two colors. Since thismodification can further enhance unnecessary light shielding effect, itis possible to further prevent malfunction in the detection of a tapeend. Although the two portions are colored with two colors, thismodification provides the same production efficiency as those of thethird and fourth embodiments and is not disadvantageous over the thirdand fourth embodiments.

FIGS. 13 and 14 show the fifth embodiment according to the presentinvention. FIG. 13 is a perspective view of the important parts of alower case portion 2 (corresponding to FIG. 8B) and FIG. 14 is aperspective view of a light shielding holder. In the fifth embodimentshown in FIG. 13, a light shielding portion 15 is provided on a wallportion 10 c right after light from a light emission element 12 comesout of a tape container 4. The light shielding portion 15 is constitutedby attaching the light shielding holder 23 shown in FIG. 14 to the wallportion 10 c.

Namely, a sensor optical path hole like that in the wall portion 10 c ofthe preceding embodiments is not provided but an area indicated bylongitudinal hatching in FIG. 13 is notched. The light shielding holder23 shown in FIG. 14 is attached to the wall portion 10 c which is formedto be short, by stopping stopper pieces 23 b at the wall portion 10 c.The light shielding holder 23 is formed out of a light shieldingmaterial with a light shielding color. A sensor optical path hole 23 ais provided in the light shielding holder 23 on a portion correspondingto the sensor optical path hole 14 c and the paired stopper pieces 23 b,23 b stopped at upper and lower wall portions 10 c (an upper caseportion side of which is not shown) are formed to protrude integrallywith each other.

This fifth embodiment, as in the case of the first embodiment, canprevent malfunction in the detection of a tape end irrespectively of thecharacteristics (color, transparency and reflectance) of a cassette case1. If the cassette case 1 itself is formed out of a high transparencymaterial, a color originally intended for the cassette case 1 can bemaintained as much as possible. Besides, since it suffices to attach thelight shielding holder 23 to the wall portion 10 c in the production ofa tape cassette, production efficiency does not extremely deterioratedifferently from the conventional tape cassette.

FIG. 15, which shows the sixth embodiment according to the presentinvention, is a perspective view of the important parts of a lower caseportion 2 (corresponding to FIG. 8B). In the sixth embodiment shown inFIG. 15, a light shielding portion 15 is provided on a wall portion 10 dnext to a portion right after light from a light emission element 12comes out of a tape container 4. The light shielding portion 15 isconstituted by attaching the light shielding holder 23 shown in FIG. 14to the wall portion 10 d. The specific constitution is the same as thatof the fifth embodiment, which description will not be, therefore, givenherein.

It can be expected that the sixth embodiment provides the same functionand advantages as those of the fifth embodiment.

As a modification of the fifth and sixth embodiments, the lightshielding holder 23 may be attached to the wall portion 10 c right afterlight from the light emission element 12 comes out of the tape container4 and to the next wall portion 10 d. Since this modification can furtherenhance unnecessary light shielding effect, it is possible to furtherprevent malfunction in the detection of a tape end. In thismodification, however, the light shielding holder 23 is attached to thetwo portions and is slightly disadvantageous in production efficiency.Nevertheless, it is sufficiently advantageous over the conventionalcassette case.

FIGS. 16A and 16B show the seventh embodiment according to the presentinvention. FIG. 16A is a side view of the cover lock member 25 and FIG.16B is a front view of the cover lock member 25. The cover lock member25 shown therein is arranged in a cover lock container 6 as shown inFIG. 8A. The cover lock member 25 is formed out of a light shieldingmaterial with a light shielding color and consists of a plate portion 25a, rotation support portions 25 b fixed to the upper end of the plateportion 25 a, respectively, a pressed portion 25 c provided to protrudefrom the lower end of the plate portion 25 a, a stopper claw 25 d forstopping a cover (not shown) and a cylindrical protrusion 25 e providedalmost at the center of the plate portion 25 a to protrude at theopposite side to the pressed portion 25 c and the stopper claw 25 d.

A sensor optical path hole 26 is provided in the cylindrical protrusion25 e. The sensor optical path hole 26 is preferably set longer as far asit does not interferes in the container 6. The cylindrical protrusion 25e is inclined downward at a cover locking position (which is a positionshown in FIGS. 16A and 16B). If the pressed portion 25 c is pressed inthe course of the insertion of a cassette, the cylindrical protrusion 25e rotates with the rotation support portion 25 b used as a fulcrum in anarrow direction in FIG. 16B and it is then put at an unlock position. Atthe unlock position, the cylindrical protrusion 25 e is put horizontallyand the sensor optical path hole 26 of the protrusion 25 e is arrangedon a straight line L1 coupling the position of the light emissionelement 12 with that of the light reception element 13 a.

According to the seventh embodiment, light advancing straight to thelight reception element 13 a, among the light from the light emissionelement 12, enters the cover lock container 6 (shown in FIG. 8A) by wayof the tape container 4 (shown in FIG. 8A) and the light is incident onthe sensor optical path hole 26 of the cylindrical protrusion 25 e. Theincident light is emitted without abutting on the inner surface of thesensor optical path hole 26 and reaches the light reception element 13 aby way of the sensor optical path hole 14 e. Conversely, theabove-stated unnecessary light does not normally advance straight to thelight reception element 13 a but is incident on the sensor optical pathhole 26 of the cylindrical protrusion 25 e, abutted on the inner surfaceof the sensor optical path hole 26 having a length M and shielded by theabsorption effect of the hole 26. In the seventh embodiment, therefore,only the cover lock member 25 is worked, so that it is possible toprevent malfunction in the detection of a tape end irrespectively of thecharacteristics (color, transparency and reflectance) of the cassettecase 1, to prevent the deterioration of production efficiency and tothereby respond to the demand of mass production. Besides, if thecassette case itself is formed out of a high transparency material, acolor originally intended for the cassette case 1 can be maintained.

While the seventh embodiment is advantageous if utilized solely asstated above, it is also possible to combine the seventh embodiment withthe first to sixth embodiments. By combining so, the advantage ofpreventing malfunction further enhances.

In the seventh embodiment, the cover lock member 25 itself is formed outof a light shielding material with a light shielding color. It is alsopossible to form only the cylindrical protrusion 25 e out of a lightshielding material with a light shielding color. It is noted, however,that the light among the unnecessary light which abuts on the plateportion 25 a and the like of the cover lock member 25 can be shielded bythe absorption effect of the cover lock member 25 if the member 25itself is formed out of a light shielding material with a lightshielding color and the unnecessary light shielding effect enhances.Thus, it is preferable that the cover lock member 25 itself is formedout of a light shielding material with a light shielding color.

FIG. 17A is a sensor output characteristic chart while colorlessness(transparency) is used as the color of the cassette case 1 and each ofthe right and left widths (light shielding range widths) D of the lightshielding portion is changed in the first to sixth embodiments. FIG. 17Bshows each of the right and left widths (light shielding range widths) Dof the light shielding portion. It is noted that the virtual line ofFIG. 17B indicates the region of the light shielding portion 15 in thefirst to sixth embodiments. Here, although already explained above, theright and left widths D of the light shielding portion 15 mean right andleft widths from the center of an optical path coupling the position ofthe light emission element 12 with that of the light reception element13 a by a straight line L1. If the width D is set at not less than 1 mm,desired light shielding effect can be obtained, which will be describedhereinafter.

In the detection of a tape end, it is assumed that a threshold value isaround 3V and the sensor malfunctions if a sensor output voltage is notless than 3V even in a state in which a magnetic recording layer tapepart is to be detected, and the sensor normally functions if the sensoroutput voltage is not more than 3V.

As shown in FIG. 17A, if a light shielding range width is zero, i.e.,the light shielding portion 15 is not at all provided around the sensoroptical path hole 14 c (or 14 d), the sensor output voltage is 5V andthe sensor malfunctions. If the light shielding portion 15 is providedaround the sensor optical path hole 14 c (or 14 d) and the width D isgradually increased, the sensor output voltage has a gradual decrease.If each of the right and left widths D of the light shielding portion 15becomes about 1 mm, the sensor output voltage is not more than 3V. Ifthe width D is not less than 2 mm, the sensor output voltage drops downto not more than 1V. This is because unnecessary light is shielded bythe shielding portion 15 and thereby the quantity of the unnecessarylight which reaches the light reception element 13 a decreases. Thisdemonstrates that the quantity of the unnecessary light which reachesthe light reception element 13 a largely depends on the right and leftwidths D of the light shielding portion 15.

The unnecessary light which reach the light reception element 13 ainclude upper and lower reflected lights reflected by the flange 5 a ofthe reel 5 or the like and right and left reflected lights reflected bythe wall portions of the cassette case 1. The upper and lower reflectedlights highly likely reach the light reception element 13 a but areshielded by the shielding portion 15. This follows that even if theentire periphery of the sensor optical path hole 14 c (or 14 d) is notshielded, unnecessary light can be effectively shielded.

As can be understood from the above and as show in FIG. 17A, even if thelateral side of the sensor optical path hole 14 c (or 14 d) is notshielded, a sensor output of not more than 3V can be held and there isless possibility of malfunction by setting the respective left and rightwidths D of the shielding portion 15 at not less than 1 mm.

FIG. 18 shows a list of malfunction evaluation results of the first andsecond embodiments and their comparison examples. A comparison example 1is a case where a light shielding portion is provided around the sensoroptical path hole 14 a of the wall portion 10 a before light from thelight emission element 12 is incident on the tape container 4. Acomparison example 2 is a case where a light shielding portion isprovided around the sensor optical path hole 14 b of the wall portion 10b before light from the light emission element is incident on the tapecontainer 4. A comparison example 3 is a case where a light shieldingportion is provided around the sensor optical path hole 14 e of the lastwall portion 10 e after light from the light emission element 12 comesout of the tape container 4.

In a sample A, the color of the cassette case is colorless(transparent). In a sample B, the color of the cassette case is smoke(translucent). In a sample C, the color of the cassette case is red(non-transparent). In a sample D, the color of the cassette case isblack (non-transparent). As a measurement equipment, a commerciallyavailable VTR was used.

The symbols of the evaluation results mean as follows. Symbol ◯ meansthat the sensor normally functions with the commercially available VTR;symbol Δ means that the detection voltage of the sensor is high and thesensor sometimes malfunction with the commercially available VTR; symbolX means that the sensor always malfunctions with the commerciallyavailable VTR. As can be seen from FIG. 18, the embodiments of thepresent invention can prevent the sensor from malfunctioning in thedetection of a tape end irrespectively of the characteristics (color,transparency and reflectance) of the cassette case 1.

FIGS. 19 and 20 show the eighth embodiment according to the presentinvention. FIG. 19 is a schematically longitudinal sectional view of atape cassette and FIG. 20 is a perspective view of the important partsof a lower case portion (corresponding to part F in FIG. 8A). The eighthembodiment will be compared with the conventional case. It is noted thatthe same constituent elements as those in the conventional case will notbe described herein to avoid repetitive description and only differentconstituent elements will be described with reference to FIGS. 19 and20.

Namely, in the eighth embodiment, a portion close to a light receptionelement 13 b is not colored with a low reflectance color unlike theconventional tape cassette. As shown in FIG. 20, a light shieldingportion 15 is provided around the sensor optical path hole 17 c of awall portion 16 c right after light from a light emission element 12comes out of a tape container 4 at a left side (supply side). The lightshielding portion 15 is constituted by bonding a light shielding memberformed out of a light shielding material to be colored with a lightshielding color to the wall portion as in the case of the firstembodiment, forming the wall portion 16 c itself out of a lightshielding material to be colored with two colors in the production ofthe cassette case 1 as in the case of the third embodiment or attachinga light shielding holder to the wall portion 16 c as in the case of thefifth embodiment.

In the detection of a tape end at the supply side, the light shieldingportion 15 is provided to have right and left widths each of not lessthan about 1 mm from the center of an optical path coupling the positionof the light emission element 12 with that of the light receptionelement 13 b by a straight line L2 and to spread over the entire heightof the wall portion 16 c. This is true for the following ninth, tenthand twelfth embodiments. The reason for setting the right and leftwidths at not less than about 1 mm is the same as that already describedabove.

With the above-stated constitution, light 22 advancing straight to thelight reception element 13 b, among the light from the light emissionelement 12, reaches a tape traveling path by way of sensor optical pathholes 17 a and 17 b. If a tape T on the tape traveling path is amagnetic recording layer tape part, it does not transmit light and thelight does not, therefore, reach the light reception element 13 b. Ifthe tape T on the tape traveling path is a high light transparencyleader tape part, it transmits light and the light reaches the lightreception element 13 b by way of the sensor optical path holes 17 c, 18a and 17 d.

Further, among light from the light emission element 12, unnecessarylight 23 which does not advance straight to the light reception element13 b and unnecessary light 23 incident into the cassette case 1 from awindow or the like on the upper surface of the tape container 4 of thetape cassette may be reflected by the upper and lower flanges 5 a and 5b of a reel 5, the inner surface of the cassette case 1 and the like anddirected toward the light reception element 13 b without passing thetape traveling path. Since most of the unnecessary light 23 which maypossibly reach the light reception element 13 b is abutted against thelight shielding portion 15 and then shielded by the portion 15, theratio of the unnecessary light which reaches the light reception element13 b is very low.

Accordingly, it is possible to prevent malfunction in the detection of atape end irrespectively of the characteristics (color, transparency andreflectance) of the cassette case. It suffices to simply bond a lightshielding member to the wall portion 16 c in the production of a tapecassette, to form the wall portion 16 c to be colored with two colors inthe production of a tape cassette or to attach the light shieldingholder to the wall portion 16 c. Unlike the conventional tape cassette,therefore, production efficiency does not deteriorate greatly.Furthermore, it suffices to bond the light shielding member 20 to onlyone wall portion 10 c which is not on the outer surface of the cassettecase 1, to form the wall portion 16 c to be colored with two colors inthe production of a tape cassette or to attach the light shieldingholder to the wall portion 16 c. Therefore, if the cassette case itselfis made of a high transparency material, a color originally intended forthe cassette case 1 can be maintained as much as possible.

FIG. 21 is a perspective view of the important parts of the lower caseportion 2 in the ninth embodiment according to the present invention. Inthe ninth embodiment, a light shielding portion 15 is provided not to aportion just after light from a light emission element 12 comes out of atape container 4 at a left side (supply side) but provided around thesensor optical path hole 17 d of the next wall portion 16 d. The lightshielding portion 15 is the same in constitution as that in the eighthembodiment.

It can be expected that the ninth embodiment provides the same functionand advantages as those of the eighth embodiment.

As a modification of the eighth and ninth embodiments, the lightshielding member 20 may be bonded around the sensor optical path hole 17c right after light from the light emission element 12 comes out of thetape container 4 and the next sensor optical path hole 17 d. Since thismodification can further enhance unnecessary light shielding effect, itis possible to further prevent malfunction in detecting a tape end. Inthis case, however, the light shielding portion 15 is provided with thetwo portions and is slightly disadvantageous in production efficiency.Nevertheless, the production efficiency of this modification issufficiently advantageous over the conventional cassette case.

FIGS. 22 and 23 show the tenth embodiment according to the presentinvention. FIG. 22 is a perspective view of the important parts of alower case 2 and FIG. 23 is a perspective view of a tape pad. In thetenth embodiment shown in FIGS. 22 and 23, the tape pad 18 itself,arranged between the sensor optical path hole 17 c of a wall portion 16c right after light from a light emission element 12 comes out of a tapecontainer 4 and the sensor optical path hole 17 d of the next wallportion 16 d, is constituted as a light shielding portion 15. Namely,while the tape pad is formed out of a transparent member in theconventional tape cassette, the tape pad 18 is formed out of a lightshielding material with a light shielding color in this embodiment andserves as the light shielding portion 15. In FIG. 22, reference symbol30 denotes a tape guide. The tape pad 18 is arranged between the tapeguide 30 and the wall portion 16 c for the purpose of preventing a tapefrom loosening.

It can be expected that the tenth embodiment provides the same functionand advantages as those of the preceding eighth and ninth embodiments.Further, in the tenth embodiment, it suffices to conduct a step ofassembling the tape pad 18 which is naturally necessary. Thus, comparedwith the conventional tape cassette, production efficiency enhances.

FIG. 24 is a perspective view of the important parts of a case portion 2in the eleventh embodiment according to the present invention. In theeleventh embodiment shown in FIG. 24, a cylindrical light shieldingmember 31 serving as a light shielding portion 15 is provided betweenthe sensor optical path hole 17 c of a wall portion 16 c right afterlight from a light emission element 12 comes out of a tape container 4at a left side (supply side) and the sensor optical path hole 17 d ofthe next wall portion 16 d and at a position at which the traveling of atape is not obstructed. The cylindrical light shielding member 31 isformed out of a light shielding material with a light shielding colorand includes therein a sensor optical path hole 31 a of a length N.

The sensor optical path hole 31 a of the cylindrical light shieldingmember 31 is preferably set longer as far as it does not obstruct thetraveling of the tape. The center of the sensor optical path hole 31 ais arranged on a straight line L2 coupling the position of the lightemission element 12 with that of the light reception element 13 b.Further, the diameter of the sensor optical path hole 31 a is set to beat least the same as that of the optical path holes 17 a to 17 d.

It can be expected that the eleventh embodiment provides the samefunction and advantages as those of the seventh embodiment. Namely,unnecessary light does not normally advance straight to the lightreception element 13 b but is incident on the sensor optical path hole31 a of the cylindrical light shielding member 31, abutted on the innersurface of the hole 31 a with the length N and shielded by theabsorption effect of the member 31. According to the eleventhembodiment, therefore, it is possible to prevent malfunction in thedetection of a tape end only by adding the cylindrical light shieldingmember 31 irrespectively of the characteristics (color, transparency andreflectance) of the cassette case 1. Besides, if the cassette case 1itself is formed out of a high transparency material, a color originallyintended for the cassette case 1 can be maintained.

FIG. 25 is a perspective view of the important parts of a case portion 2in the twelfth embodiment according to the present invention. In thetwelfth embodiment shown in FIG. 25 as in the case of the eleventhembodiment, a light shielding wall portion 32 is newly provided betweenthe sensor optical path hole 17 c of a wall portion 16 c right afterlight from a light emission element 12 comes out of a tape container 4at a left side (supply side) and the sensor optical path hole 17 d ofthe next wall portion 16 d and at a position at which the traveling of atape is not obstructed. The light shielding wall portion 32 is formedout of a light shielding material with a light shielding color. A sensoroptical path hole 32 a is formed in the light shielding wall portion 32.The center of the sensor optical path hole 32 a is arranged on astraight line L2 coupling the position of the light emission element 12with that of the light reception element 13 b. Further, the size of thesensor optical path hole 32 a is set to be the same as at least that ofthe sensor optical path holes 17 a to 17 d. This light shielding portion32 is constituted by separately attaching the portion 32 to the cassettecase after the cassette case has been manufactured or by forming theportion to be colored with two colors in the production of the cassettecase.

It can be expected that the twelfth embodiment provides the same lightshielding effect as those of the eighth and ninth embodiments.

While the eleventh or twelfth embodiment provides advantages if usedsolely as stated above, it is also possible to combine it with theeighth to tenth embodiments. By combining so, the advantage ofpreventing malfunction further enhances.

FIG. 26 shows a list of malfunction evaluation results of the eighth toeleventh embodiments and their comparison examples. A comparison example4 is a case where a light shielding portion is provided around thesensor optical path hole 17 a of a wall portion 16 a just before lightfrom a light emission element 12 is incident on a tape container 4. Acomparison example 5 is a case where a light shielding portion isprovided around the sensor optical path hole 17 b of a wall portion 16 bjust before light from the light emission element 12 is incident on atape container 4. A comparison example 6 is a case where no lightshielding measures are taken.

In a sample A, the color of the cassette case is colorless(transparent). In a sample B, the color of the cassette case is smoke(translucent). In a sample C, the color of the cassette case is red(non-transparent). In a sample D, the color of the cassette case isblack (non-transparent). As a measurement equipment, a commerciallyavailable VTR was employed.

The symbols of the evaluation results mean as follows. Symbol ◯ meansthat the sensor normally functions with the commercially available VTR.Symbol X means that the sensor always malfunctions with the commerciallyavailable VTR. As can be understood from FIG. 26, the embodiments of thepresent invention can prevent the sensor from malfunctioning in thedetection of a tape end irrespectively of the characteristics (color,transparency and reflectance) of the cassette case 1.

FIG. 27 is a schematically longitudinal sectional view in the thirteenthembodiment according to the present invention. In the thirteenthembodiment shown in FIG. 27, both an upper flange 5 a and a lower flange5 b of each of a pair of reels 5, 5 are formed out of a materialattenuating a reflected light with a color (e.g., black) attenuatingreflected light. In FIG. 27, the upper flange 5 a and the lower flange 5b of the respective paired reels 5, 5 are indicated by hatching.

According to the thirteenth embodiment, unnecessary light 23 which doesnot advance straight to a light reception element 13 b and unnecessarylight 23 which is incident into a cassette case 1 from a window and thelike on the upper surface of the tape container 4 of the tape cassette,among the light from a light emission element 12, are abutted on theinner surfaces of the upper and lower flanges 5 a and 5 b of the reels 5and the reflected light is attenuated, i.e., shielded by the absorptioneffect of the flanges. Therefore, according to the thirteenthembodiment, it is possible to prevent malfunction in the detection ofthe tape end only by installing the reels 5 subjected to light shieldingprocessing irrespectively of the characteristics (color, transparencyand reflectance) of the cassette case 1. Besides, production efficiencydoes not deteriorate and it is, therefore, possible to deal with thedemand of mass production. Moreover, if the cassette case 1 itself isformed out of a high transparency material, a color originally intendedfor the cassette case 1 can be maintained.

While both of the paired reels 5, 5 are subjected to light shieldingprocessing in the thirteenth embodiment, only one of the right side(take-up side) and the left side (supply side) of the reels may besubjected thereto. Further, while both the upper flange 5 a and thelower flange 5 b of each of the paired reels 5 are subjected to lightshielding processing in the thirteenth embodiment, only one of the upperflange 5 a and the lower flange 5 b may be subjected thereto.

While the thirteenth embodiment provides advantages if used solely asstated above, it is also possible to combine the thirteenth embodimentwith the preceding first to seventh embodiments or eighth to twelfthembodiments. By combining so, the advantage of preventing malfunctionfurther enhances.

While the constitutions of the tape cassette regarding the detection ofa tape end at the take-up side in the first to seventh embodiments donot show the light shielding means disclosed by the eleventh and twelfthembodiments, the light shielding means disclosed by the eleventh andtwelfth embodiments can be also applied to the take-up side.

(Tape Cassette in Embodiments Regarding the Presence/Absence of the TapeCassette)

FIGS. 28 to 31 show the fourteenth embodiment according to the presentinvention. Specifically, FIG. 28A is a plan view of a tape cassette fromwhich only the upper portion of a cassette case is removed; FIG. 28B isa back view of the tape cassette; FIG. 28C is a side view of the tapecassette; FIG. 29 is a partial enlargement view of part MM of FIG. 28A;FIG. 30 shows the optical path of detected light incident on a prismportion on the side surface of the tape cassette; and FIG. 31 shows theoptical path of detected light incident on a prism portion on the backsurface thereof.

With reference to FIGS. 28A to 28C, description will be given to thecassette presence detection means 112 at the side of an apparatus (arecording and reproducing apparatus, a cassette changer or the like) inwhich the tape cassette TTC in the fourteenth embodiment is used. Thecassette presence detection means 112 includes a light emission portion112 a provided at the apparatus side and a light reception portion 112 bfor receiving detected light from the light emission portion 112 a. Thecassette presence detection means 112 is set so that the optical pathCC1 (the center of which is shown therein) of detection light reachingthe light reception portion 112 b from the light emission portion 112 apasses a cassette position by going from the side surface side of thetape cassette TTC through the front surface side thereof. To be exact,the detection light is emitted from the light emission portion 112 a ata light emission angle of about 30 degrees (15 degrees at one side).

Meanwhile, the cassette case 120 of the tape cassette TTC has agenerally flat, rectangular parallelopiped shape consisting of an uppersurface portion 120 a, a bottom portion 120 b, a pair of right and leftside surface portions 120 c, a front surface portion 120 d and a backsurface portion 120 e. The cassette case 120 is made of a hightransparency material (e.g., polystyrene). A partition wall 122 isprovided in the cassette case 120 to form a pair of tape containers 121,121 and a pair of wound tapes (not shown) are rotatably contained in thepaired containers 121, 121 respectively.

Prism portions 123 and 124 are provided on a portion of the cassettecase 120 which portion corresponds to that on the optical path CC1 ofthe detected light and on which portion the detection light emitted fromthe light emission portion 112 a is first incident, or to be specific,on part of the side surface portion 120 c and the back surface portion120 e adjacent the side surface portion 120 c, respectively (FIG. 28Ashows an area in which the prism portions 123 and 124 are provided isindicated by hatching).

The prism portions 123 and 124 on the side surface portion 120 c and theback surface portion 120 e, respectively, are formed continuously inparallel as shown in FIG. 29. They are formed simultaneously with theformation of the cassette case 120 in an integral fashion. The prismportion 123 on the side surface portion 120 c is formed to have avertical angle of 30 degrees, whereas the prism portion 124 on the backsurface portion 120 e is formed to have a vertical angle of 60 degrees.

With the above-stated constitution, if the tape cassette TTC is put atthe cassette position of the apparatus, the detection light from thelight emission portion 112 a is applied thereto about the optical pathCC1. As shown in FIG. 30, this detection light is incident on the sidesurface portion 120 c at the center of an incident angle of almost 70degrees (an angle with respect to an incident normal LL1) and emitted atan emission angle of 23 degrees with respect to the incident normal LL1by the refraction of the prism portion 123. Accordingly, the detectionlight is emitted in a direction largely deviated from the optical pathCC1 of the incident light. The angle of deviation of the prism portion123 (difference between the incident angle and the emission angle) is 47degrees.

As shown in FIG. 31, the detection light is incident on the back surfaceportion 120 e of the tape cassette TTC at the center of the incidentangle of almost 40 degrees (an angle with respect to an incident normalLL2) and emitted to the emission surface 124 a of the prism portion 124at a projection angle of 54.5 degrees. Since the critical angle of theprism portion 124 is almost 40 degrees, the detection light is,therefore, totally reflected. Accordingly, the detection light isemitted in a direction largely deviated from the optical path CC1 of theincidence light. As can be seen from the above, the detection lightapplied to the tape cassette TTC hardly reaches the light receptionportion 112 b by the refraction or reflection of the prism portions 123and 124 and it is possible to prevent a cassette detection error in thetape cassette TTC with the high transparency cassette case 120.

While the prism portion 123 on the side surface portion 120 c is formedto have a vertical angle of 30 degrees and the prism portion 124 on theback surface portion 120 e is formed to have a vertical angle of 60degrees in the fourteenth embodiment, the prism portions 123 and 124 maybe formed so as to refract or reflect incident light in the emissiondirection in which the light does not reach the light reception portions112 b.

FIG. 32, which shows the fifteenth embodiment according to the presentinvention, shows prism portions arranged on part MM of FIG. 28A in apartially enlarged view. In the fifteenth embodiment, an inner wall 130parallel to the side surface portion 120 c is formed inside the cassettecase 120 in addition to the prism portion 123 on the side surfaceportion 120 c and the prism portion 124 on the back surface portion 120e of the fourteenth embodiment. A prism portion 123 is formed on onesurface of the inner wall 130 to have the same vertical angle of 30degrees as that of the prism portion 123 on the side surface portion 120c. The remaining constitution is the same as that of the fourteenthembodiment. The inner wall 130 is formed to reach a partition inner wall122. With the inner wall 130, incident light leaked in the corner (inthe form of R) 120 f in which the side surface portion 120 c and theback surface portion 120 e cross each other, can be refracted, among thelight from the side surface portion 112 a, in an emission direction inwhich the light does not reach the light reception portion 112 b.Accordingly, it is possible to prevent a cassette detection error in thetape cassette TTC with the high transparency cassette case 120.

FIGS. 33 to 35 show the sixteenth embodiment according to the presentinvention. Specifically, FIG. 33A is a plan view of a tape cassette fromwhich only the upper surface portion of a cassette case is removed; FIG.33B is a back view of the cassette case; FIG. 33C is a side view of thecassette case; FIG. 34 is a partially enlarged view of part NN of FIG.33C; and FIG. 35 shows the optical path of detection light incident on aprism portion on the bottom surface.

With reference to FIGS. 33A to 33C, description will be given first tocassette presence detection means 113 at the side of an apparatus inwhich the tape cassette TTC in the sixteenth embodiment is used. Thecassette presence detection means 113 has a light emission portion 113 aprovided at the apparatus side and a light reception portion 113 b forreceiving detection light from the light emission portion 113 a. Thecassette presence detection means 113 is set so that the optical pathCC2 (the center of which is shown therein) of the detection lightreaching the light reception portion 113 b from the light emissionportion 113 a may pass a cassette position by going from the bottom sideof the tape cassette TTC through the upper surface side thereof.Actually, the detection light is emitted from the light emission portion113 a at an emission angle of about 30 degrees (15 degrees at one side).

Meanwhile, the cassette case 120 of the tape cassette TTC has agenerally flat, rectangular parallelopiped shape consisting of an uppersurface portion 120 a, a bottom portion 120 b, a pair of right and leftside surface portions 120 c, 120 c, a front surface portion 120 d and aback surface portion 120 e and formed out of a high transparencymaterial (e.g., polystyrene). A partition inner wall 122 forming a pairof tape containers 112 is provided inside the cassette case 120. A pairof wound tapes (not shown) are rotatably contained in the paired tapecontainers 121, 121, respectively.

A prism portion 125 is provided on a portion of the cassette case 120which portion corresponds to that on the optical path CC2 of thedetection light and on which the detection light emitted from the lightemission portion 113 a is incident first, to be specific, on part of thebottom portion 120 b (an area in which the prism portion 125 is providedis indicated by hatching to clarify the position thereof in FIG. 33A).

As shown in FIG. 34, the prism portion 125 is formed continuously inparallel and formed simultaneously with the formation of the cassettecase 120 in an integrally fashion. The prism portion 125 on the bottomportion 120 b is formed to have a vertical angle of 30 degrees.

With the above-stated constitution, if the tape cassette TTC is put atthe cassette position of the apparatus, the detection light from thelight emission portion. 113 a is applied thereto about the optical pathCC2. As shown in FIG. 35, this detection light is incident on the bottomportion 120 b of the tape cassette TTC at the center of an incidentangle of almost 20 degrees (an angle with respect to an incident normalLL3) and emitted at an emission angle of 49 degrees with respect to theemission surface 125 a of the prism portion 125. Since the criticalangle of the prism portion 125 is almost 40 degrees, the detection lightis, therefore, totally reflected. Accordingly, the detection light isemitted in a direction largely deviated from the optical path CC2 of theincidence light. As can be seen from the above, the detection lightapplied to the tape cassette TTC hardly reaches the light receptionportion 113 b by the reflection of the prism portion 125 and it ispossible to prevent a cassette detection error in the tape cassette TTCwith the high transparency cassette case 120.

While the prism portion 125 on the bottom portion 120 b is formed tohave a vertical angle of 30 degrees in the sixteenth embodiment, theprism portion 125 may be formed so as to refract or reflect incidentlight in the emission direction in which the light does not reach thelight reception portions 112 b.

FIGS. 36A to 36C show the seventeenth embodiment according to thepresent invention. Specifically, FIG. 36A is a plan view of a tapecassette from which only the upper surface portion of a cassette case isremoved; FIG. 36B is a back view of the tape cassette; and FIG. 36C is aside view of the tape cassette.

In FIGS. 36A to 36C, the tape cassette TTC is constituted to beapplicable to both the apparatuses in the fourteenth(fifteenth) andsixteenth embodiments. Namely, prism portions 123, 124 and 125 areprovided on portions of the cassette case 120 corresponding to those onthe two optical paths CC1 and CC2 of the detection light (the sidesurface portion 120 c of the cassette case 120 and part of the backsurface portion 120 e adjacent the side surface portion 120 c asdescribed in the fourteenth and fifteenth embodiments and part of thebottom portion 120 b as described in the sixteenth embodiment),respectively (FIG. 36A shows an area in which the prism portions 123,124 and 125 are provided is indicated by hatching to clarify thepositions thereof). The constitutions of the respective prism portions123, 124 and 125 are the same as those described in the fourteenth (orfifteenth) embodiment and the sixteenth embodiment, which descriptionwill not be given herein to avoid repetitive description.

In the tape cassette TTC in the seventeenth embodiment, even if it isused in either the apparatus in the fourteenth (or fifteenth) embodimentor that in the sixteenth embodiment, detection light applied to the tapecassette TTC hardly reaches the light reception portions 112 b and 113 bby either the refraction or reflection of the prism portions 123, 124and 125. It is, therefore, possible to prevent a cassette detectionerror in the tape cassette TTC with the high transparency cassette case120.

In the above-stated fourteenth to seventeenth embodiments, since theprism portions 123, 124 and 125 are formed integrally with the cassettecase 120 and they are formed simultaneously with the cassette case 120,the production of the prism portions 123, 124 and 125 is easy andproduction cost can be reduced. Alternatively, the prism portions 123,124 and 125 may be produced separately from the cassette case 120 andthen attached to the cassette case.

In the above-stated fourteenth, fifteenth and seventeenth embodiments,since the prism portion 123 is provided on the portion of the cassettecase 120 on which portion detection light emitted from the lightemission portion 112 a is first incident, the distance from the prismportion 123 to the light reception portion 112 b is long. Thus, it ispossible to prevent the detection light from reaching the lightreception portion 112 b even if the deviation angle of the prism portion123 is set small, whereby the degree of freedom for the design of theprism portion 123 increases. Alternatively, the prism portion may beprovided on the portion of the cassette case 120 on which the detectionlight emitted from the light emission portion 112 a is incident notfirst but second, to be specific, on the front surface portion 120 d.

In the above-stated fourteenth to seventeenth embodiments, since theprism portions 123, 124 and 125 are provided on the inner surface of thecassette case 120, there is little possibility that the surfaces of theprism portions 123, 124 and 125 are damaged or the like by friction,scratch or the like.

In the meantime, light shielding members may be provided at thepositions of the prism portions 123, 124 and 125 so as to obtain thesame advantages as those of the present invention. However, if the prismportions 123, 124 and 125 are formed integrally with the cassette case120, an assembly step is not necessary compared with a case where thelight shielding members are provided. Thus, this embodiment isadvantageous in that problems such as attachment error and peeling donot occur and also excellent in design.

The above-stated fourteenth to seventeenth embodiments illustrate anexample of the tape cassette TTC which can be applied to a case wherethe optical path CC1 of the detection light passes the cassette positionby going from the side surface side of the tape cassette TTC through thefront surface side thereof and to a case where the optical path CC2 ofthe detection light passes the cassette position by going from thebottom side of the tape cassette TTC through the upper surface sidethereof. It goes without saying that the present invention is alsoapplicable to cases of optical paths other than CC1 and CC2.

In the above-stated fourteenth to seventeenth embodiments, the prismportions 123, 124 and 125 are provided only on the portions of thecassette case 120 corresponding to those on the optical paths CC1 andCC2. If similar prism portions 123, 124 and 125 are providedsymmetrically about a vertical axis, the design of the resultant tapecassette becomes more excellent and the degree of freedom for the designof the cassette presence detection means 112 and 113 increasesaccordingly.

FIGS. 37 to 39 show the eighteenth embodiment according to the presentinvention. Specifically, FIG. 37 is a partially plan view of a tapecassette TTC from which the upper surface side of a cassette case 120 isremoved; FIG. 38 is a perspective view of the important parts of thetape cassette showing a state before a light shielding member 117 isattached; and FIG. 39 is a perspective view of the important partsthereof showing a state that the light shielding member 117 has beenattached.

In FIG. 37, cassette presence detection means 112 at the side of anapparatus in which the tape cassette TTC in the eighteenth embodiment isused is the same as that in the fourteenth (or fifteenth) embodiment.Therefore, the means 112 is denoted by the same reference symbol as thatin the fourteenth (or fifteenth) embodiment and no description will begiven thereto. Further, tape end detection means 114 is provided at theapparatus side. The tape end detection means 114 is provided with alight emission portion 114 a and a pair of tape end detection lightreception portions (one of which is not shown therein) for receivingdetection light from the light emission portion 114 a. While the tapecassette TTC is being attached to the apparatus, the light emissionportion 114 a is arranged in a wall portion 115 a having a cylindricalcenter and the paired light reception portions 114 b are arranged atexternal positions on the right and left sides of the tape cassette TTC,respectively.

The cassette case 120 of the tape cassette TTC is constituted in thesame manner as that in the fourteenth embodiment and formed out of ahigh transparency material. The wall portion 115 a, a partition innerwall 122, a wall portion 115 b and a side surface portion 120 c on thetape end detection optical path CC3 coupling the light emission portion114 with the light reception portion 114 b of the tape end detectionmeans 114 are provided with optical passages 116 a to 116 e,respectively. A light shielding member 117 is attached to the portion ofthe light passage 116 d of the wall portion 115 b. A light passage 117 ais opened on the portion of the light shielding member 117 which portioncontact with the optical path CC3. The light passage 117 a isconstituted to pass detection light passing on the optical path CC3 andto prevent the passage of unnecessary light deviated from the opticalpath CC3. That is, with this constitution, even if the cassette case 120is formed out of a high transparency material, it is possible to ensurepreventing erroneous detection of a tape end.

Furthermore, one end of the light shielding member 117 is formed largeand extended to exceed the degree to which the portion of the lightpassage 116 d on the wall portion 115 b is blocked. This extendedportion 117 b is clinched with respect to the portion on which the lightpassage 117 a is provided and arranged on the cassette presencedetection optical path CC1.

In this eighteenth embodiment, only the light passing through theoptical path CC3, among the detection light for the detection of a tapeend, passes through the light passage 117 a of the light shieldingmember 117 and the passage of light deviated from the optical path CC3is prevented by the light shielding member 117. Owing to this, if thecassette case is made of a high transparency material, it is possible toensure preventing the erroneous detection of a tape end. In addition,the passage of the cassette presence detection light is prevented by theextended portion 117 b of the light shielding member 117. Owing to this,if the cassette case is made of a high transparency material, it ispossible to ensure preventing the erroneous detection of the presence ofa cassette. Further, in case of preventing the erroneous detection ofthe presence of a cassette, the light shielding member 117 forpreventing the erroneous detection of a tape end is utilized. Due tothis, it is possible to prevent the erroneous detection of the presenceof a cassette without increasing the number of parts and withoutdeteriorating assemblage.

FIG. 40, which shows the nineteenth embodiment according to the presentinvention, is a plan view of a tape cassette from which only the uppersurface portion of a cassette case is removed. FIG. 41A is anexplanatory view of the tape cassette for the surrounding of an opticalpath notch of the cassette case. FIG. 41B shows the optical path of tapeend detection light while a prism portion is provided. FIG. 41C showsthe optical path of tape end detection light while a prism portion isnot provided.

The nineteenth embodiment is intended to prevent a tape end detectionerror (tape terminal end detection error) in a tape cassette TTC inwhich tape end detection light CC3 passes through portions other thanoptical path notches of a high transparency cassette case 120 in asystem in which high transparency leader tapes are provided on the bothends of a magnetic tape and a tape terminal end is detected while usingtape end detection light (tape terminal end detection light) CC3 fromthe light emission portion 114 a of tape end detection means 114. Thatis, optical path notches 122 d and 122 e are formed in right and leftpartition walls 122, 122 around tape end detection notches 122 b and 122c on the both sides of a right semicylindrical wall 122 a constitutingthe insertion hole of the light emission portion 114 a for the detectionof a tape end, respectively. Prism portions 126 and 127 for refractingor reflecting the tape end detection light CC3 from the light emissionportion 114 a in a direction in which the light does not reach the rightand left light reception portions 114 b, 114 b, are provided on thepartition walls 122 around the notches 122 d and 122 e, respectively.

Further, prism portions 128 and 129 for refracting or reflecting thetape end detection light CC3 from the light emission portion 114 a in adirection in which the light does not reach the right and left lightreception portions 114 b, 114 b, are provided on walls around opticalpath notches 122 f and 122 g at the front sides of the right and leftside surface portions 120 c of the cassette case 120, respectively. Theremaining constituent elements are the same as those in the fourteenthembodiment. Accordingly, the same constituent elements are denoted bythe same reference symbols and detailed description will not be giventhereto.

According to the tape cassette TTC in the nineteenth embodiment, thetape end detection light CC3 hardly reaches the right and left lightreception portions 114 b, 114 b by the refraction or reflection of therespective prism portions 126 to 129, thereby making it possible toprevent a tape end detection error in the tape cassette TTC with thehigh transparency cassette case 120.

As shown in FIGS. 41A and 41B, if the prism portion 126 is providedaround the notch 112 d through which the tape end detection light CC3passes, the light from the light emission portion 114 a does not advancestraight as shown in FIG. 41B and is refracted or reflected in adirection in which the light does not reach the light reception portion114 b. In theory, the prism portion may be formed on one surface.However, if the angle of the incident light on the prism portion issmall and the prism portion is formed integrally with the cassette case120, the advancing components of the light are left due to the curvedportion (R portion) provided at the peak or in the corner of the prismportion and surface property thereof and they reach the light receptionportions to thereby cause malfunction. In view of this, therefore, ifthe prism portions 126 to 129 are provided on a plurality of portions ofthe partition inner wall 122 as shown in FIG. 40, the prevention ofmalfunction is more ensured.

Needless to say, in case of detecting a tape end and detecting whetheror not a tape cassette is present, the first to nineteenth embodimentsdescribed so far can be arbitrarily selected and combined.

It should be understood that many modifications and adaptations of theinvention will become apparent to those skilled in the art and it isintended to encompass such obvious modifications and changes in thescope of the claims appended hereto.

What is claimed is:
 1. A tape cassette comprising: a cassette case having a top face portion, an under face portion, a front face portion, a rear face portion, and a pair of side face portions of right and left sides; a pair of tape containers of supply and take-up sides provided in said cassette case; a tape wound around a pair of reels and contained in the pair of tape containers; a first wall portion connecting the rear face portion and the right side face portion with each other and forming part of the take-up side tape container; a second wall portion connecting the rear face portion and the left side face portion with each other and forming part of the supply side tape container; and a first prism portion extending from at least a part of the rear face portion to at least a part of the right side face portion and refracting or reflecting light from a light emission element of the recording and reproducing apparatus for detecting presence and absence of said tape cassette to prevent the light from reaching a light reception element of the recording and reproducing apparatus.
 2. A tape cassette according to claim 1, if wherein said first prism portion and said cassette case are integrally formed.
 3. A tape cassette according to claim 1, further comprising a third wall portion connecting the rear face portion and the first wall portion with each other and having a second prism portion refracting or reflecting the light from the light emission element of the recording and reproducing apparatus for detecting presence and absence of said tape cassette to prevent the light from reaching a second light reception element of the recording and reproducing apparatus.
 4. A tape cassette according to claim 3, wherein said second prism portion and said cassette case are integrally formed.
 5. A tape cassette comprising: a cassette case having a top face portion, an under face portion, a front face portion, a rear face portion, and a pair of side face portions of right and left sides; a pair of tape containers of supply and take-up sides provided in said cassette case; a tape wound around a pair of reels and contained in the pair of tape containers; a first wall portion connecting the rear face portion and the right side face portion with each other and forming part of the take-up side tape container; a second wall portion connecting the rear face portion and the left side face portion with each other and forming part of the supply side tape container; and a prism portion provided on at least a part of a region of the under face portion and refracting or reflecting light from a light emission element of the recording and reproducing apparatus for detecting presence and absence of said tape cassette to prevent the light from reaching a light reception element of the recording and reproducing apparatus, said region being enclosed by the rear face portion, the left side face portion and said second wall portion.
 6. A tape cassette according to claim 5, wherein said prism portion and said cassette case are integrally formed. 